I. Field of the Invention
This invention relates generally to trailer jacks for raising and lowering a trailer tongue and coupler relative to a hitch ball on a towing vehicle, and more particularly to such a trailer jack having a steerable, powered wheel for moving a trailer to facilitate alignment of the tongue mounted coupler with the hitch ball or for otherwise repositioning the trailer at a desired location.
II. Discussion of the Prior Art
Motorized, directionally steerable trailer tongue jacks are known in the art. U.S. Pat. No. 6,779,616 to Brown describes a device having a height adjustment power transmission screw and a drive and steering system for the jack's wheel. The drive is an electronically remote controlled dc motor whose output shaft directly drives the wheels' axle. Separate electric motors are also used for elevation and steering which unduly increases the complexity and cost of the trailer jack.
The Moreau et al. U.S. Pat. No. 6,945,343 describes a motorized trailer jack in which a dc motor has its output shaft coupled through a pinion gear to a toroidal rack gear affixed to the wheel. While this simplified drive arrangement overcomes objections to the device described in the Brown '616 patent, it presupposes that easy access to a 12 volt battery source is always available and no means are provided for driving the wheel in the event that a 12 volt connector is not available at the hitch of the towing vehicle.
A need, therefore, exists for a trailer jack having a powered wheel that may be driven either electrically by means a motor or mechanically through a manually actuated transmission. The present invention provides such a need.